1. Field of the Invention
The present invention relates to machine tools for cutting circles and more particularly such a tool adapted for use with a drill press, electric hand drill or similar machine for cutting circles or segments of circles of selected diameter.
2. Description of the Prior Art
Various devices have been taught in the prior art for cutting circles in a workpiece. Typical of such prior art devices are those adapted for use with a drill press or a milling machine and in which a stationary cutting tool is fixedly mounted to a rotating frame at a selected radius from the axis of rotation of the drill press or the like. Such devices have the disadvantage of being unbalanced and, accordingly, limited to slow speed operation. Another type of such device, disclosed in U.S. Pat. No. 3,263,570 to Heffron et al., discloses an attachment for machine tools which utilizes a geared connection between the machine tool output shaft and the cutting tool. The cutting tool is rotated about its own axis and this axis is, in turn, rotated about an axis spaced at a selected distance from the axis of the machine tool to permit cutting arcuate slots or circular holes. This device, is adapted for use as an attachment with a stationary milling machine. It does not have its own pilot center, is not portable for use with a hand drill, cannot be used in cutting radial slots, and is limited in use to a small radius variation depending upon the diameter of the floating idler gear.